1. Field of the Invention
This invention relates to an improved optical touch panel.
2. Description of the Prior Art
FIG. 4 shows the construction of a conventional optical touch panel.
The optical touch panel 101 has a plurality of light-emitting elements 110 arranged along two adjacent sides of a rectangular position-detecting surface 150 and a plurality of light-receiving elements 130 arranged along the other two sides of the same such that the light-emitting elements 110 are opposed to the respective light-receiving elements 130 with the position-detecting surface 150 therebetween.
A control block 140 causes the light-emitting elements 110 to light sequentially from left to right and from top to bottom as viewed in FIG. 4, and causes the light-receiving elements 130 to receive lights from the respective light-emitting elements 110 opposed thereto.
In the optical touch panel 101, optical paths are formed on the position-detecting surface 150 in a grid pattern.
When an object 170 lies in a position shown in FIG. 4, the object 170 blocks some optical paths to thereby hinder lights from the corresponding light-emitting elements 110 from reaching light-receiving elements 130 opposed to the light-emitting elements 110. As a result, the control block 140 detects the position (two dimensional coordinates) of the object 170 based on information of received lights from the light-receiving elements 130.
In the above optical touch panel 101, however, it is required to arrange elements 110, 130 along the four sides of the rectangular position-detecting surface 150, and hence it takes a lot of time for establishing wire connections of the elements.
To solve the problem, another optical touch panel constructed as below was proposed.
FIG. 5 shows the construction of this prior art optical touch panel.
The optical touch panel 201 is comprised of light-emitting elements 210, two reflectors 220 for reflecting lights from the light-emitting elements 210, and light-receiving elements 230 for receiving the reflected lights from the reflectors 220.
The light-emitting elements 210 and the light-receiving elements 230 are alternately arranged along two adjacent sides of a rectangular position-detecting surface 250, and the reflectors 220 are arranged along the other two adjacent sides of the rectangular position-detecting surface 250.
When an object 270 lies in a position shown in FIG. 5, the object 270 blocks some optical paths to thereby hinder lights from the reflectors 220 from reaching the light-receiving elements 230 opposed to the object 270. As a result, a control block 240 detects the position of the obstacle 270 based on information of received lights from the light-receiving elements 230.
This optical touch panel makes it possible to simplify wiring, compared with the FIG. 4 conventional touch panel.
However, the FIG. 5 optical touch panel uses a pair of elements (i.e. a light-emitting element 210 and a light-receiving element 230) per one optical path, so that it is required to provide numerous light-emitting and light-receiving elements, which results in an increase in manufacturing costs.
It is an object of the invention to provide an optical touch panel having a construction which makes it possible to decrease the number of elements, thereby reducing manufacturing costs.
To attain the above object, the present invention provides an optical touch panel including a plurality of light-emitting means, reflector means for reflecting lights from the plurality of light-emitting means, and a plurality of light-receiving means for receiving reflected lights from the reflector means, the plurality of light-emitting means and the plurality of light-receiving means being arranged alternately along two adjacent sides of a rectangular position-detecting surface, the reflector means being arranged along each of other two adjacent sides of the position-detecting surface.
The optical touch panel according to the invention is characterized by comprising:
control means that causes the plurality of light-emitting means to light in a predetermined order to thereby cause ones of the plurality of light-receiving means arranged on opposite sides of each of the plurality of light-emitting means to receive reflected lights from the reflector means; and
blocking means that inhibits lights other than the reflected lights reflected by the reflector means from being incident on the plurality of light-receiving means.
According to this optical touch panel, when an object lies on one of two optical paths simultaneously formed in a manner extending from one light-emitting means to corresponding two light-receiving means, i.e. two light-receiving means arranged on respective opposite sides of the one light-emitting means, one of the two light-receiving means on one side of the lit light-emitting means receives a reflected light from the reflector means, whereas the other of the two light-receiving means on the other side does not receive the reflected light. These results are delivered as received-light information from the two light-receiving means to the control means. The control means detects the position of the object based on received-light information delivered from the light-receiving means arranged along the two sides of the position-detecting surface. It should be noted that lights reflected off the object on the position-detecting surface are blocked by the blocking means and inhibited from being incident on the light-receiving means, and therefore it is possible to detect the position of the object without any error.
Preferably, the blocking means is formed by a plurality of hollow cylinders opposed to light-receiving surfaces of the plurality of light-receiving means, respectively.
According to this preferred embodiment, lights from optical paths other than predetermined optical paths are blocked by the peripheral wall of each hollow cylinder and inhibited from being incident on the light-receiving surfaces of the light-receiving means.
Alternatively, the blocking means is formed by plates formed with a plurality of through holes opposed to light-receiving surfaces of respective corresponding ones of the plurality of light-receiving means.
According to this preferred embodiment, lights from optical paths other than predetermined optical paths are blocked by the plates and inhibited from being incident on the light-receiving surfaces of the light-receiving means.
More preferably, the optical touch panel further comprises a plurality of condensing lenses for each condensing a light emitted from a corresponding one of the plurality of light-emitting means such that the condensed light is directed in a predetermined direction.
According to this preferred embodiment, a light emitted from each of the plurality of light-emitting means is condensed such that the condensed light is directed in a predetermined direction and then reflected by the reflector means to be incident on the associated light-receiving means.
The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with accompanying drawings.